Anyone who's followed football in Italy will know that last night's events at the San Siro were no one-off. The throwing of flares and missiles at the pitch or the opposition fans are a regular feature at many Italian stadia.

The incidents aren't usually as dramatic as last night's, when Milan's Brazilian goalkeeper Dida was struck by a burning flare hurled from the upper tier, but on occasion they are. Remember referee Anders Frisk's bloodied face after he was hit by a coin thrown by Roma fans at the Stadio Olimpico last September? Or, three years ago, Inter fans' attempts to launch a burning scooter from the same Curva Nord that hosted last night's scenes?

The problem in Italy is simple, even if the solution isn't. The Curvas, the areas where the hardcore supporters go, are seen as Ultra territory and the police do not and will not enforce the law there. This was underlined again just last weekend when Lazio supporters at the Stadio Olimpico unveiled a giant banner boasting "Rome is Fascist" and happily waved Nazi flags throughout the game. Both acts are against the law in Italy, but no attempt was made to stop them.

I once asked an Italian policeman regularly assigned to stadium duty what the story was. He admitted that the police avoid entering Ultra territory for fear of provoking a riot. If they ever do go in (say, if English fans are present) then it's with full body armour and truncheons to crack some heads, but this is rare. Many in Italy feel the "English model" - numbered seats and club stewards backed by officers quietly identifying and removing troublemakers - is the solution; but to introduce it would mean ending the power of the Ultra groups, and that won't be easy.

Italian supporters' groups enjoy a level of influence on their clubs without parallel in top-flight football: they can dissuade a club from signing a player, as in the case of Ronnie Rosenthal to Udinese; conduct negotiations with a transfer target, like when the Lazio fans' infamous delegation travelled to the Parma training ground to try and talk Lilian Thuram into joining the Rome club (wonder why that one fell through?); they can enter locker rooms to "encourage" under-performing players (er, Lazio again); and, like last night, they can force games to be abandoned - remember the derby last year, when four Roma fans used an ill-founded rumour of police brutality to enter the pitch and convince captain Francesco Totti to stop the match? Yesterday, in frustration at their umpteenth defeat to Milan, it looked like a group of Inter fans were after a similar show of force, unveiling, even before the barrage began, a banner declaring "We Don't Care About the Match Anyway".

Will things ever change? Today's papers will be full of proposals to reign the Ultras back in, while politicos from Berlusconi down (or up) promise crackdowns and shake-ups. However, before a year is out they'll probably be doing it all over again for some other "Night of Shame".

The fact that this time it's one of Italy's big three clubs and under Uefa jurisdiction may make a difference, but don't bet on it. Way back in 1998, fans in Salerno went way better than these interisti when, during a Fiorentina-Grasshoppers Zurich Uefa Cup match [what, you ask, were Fiorentina doing playing down in Salerno? Serving a stadium ban in Florence, of course] they hit one of the match officials with a home-made bomb they'd smuggled into the ground. Uefa "cracked down" after that one, too, and just look how much effect that had.